Electric heating plate



June 13, 1939. 5 cu g-r 2,161,781

ELECTRIC HEATING PLATE Filed Oct.. 28. 1937 Patented June 13, 1939PATENT OFFICE ELECTRIC HEATING Etienne Challet, Paris, FranceApplication October 28, 1937, Serial No. 171,575 I In SwitscrlandJanuary 13, 1937 iclaims.

To assure a satisfactory contact oi the insulating unit containing theheating element with the under-surface of an electric heating plate, ithas already been proposed to utilize a press- 5 ing member composed of aseries oi mica leaves unconnected by binding material; but this materialhas a disadvantage, i. e. that its pressing capacity will decrease incourse of time.

The object of the invention is an electric heatli) ing plate, in whichthe insulating unit containing the heating element is applied againstthe plate by means of a pad of mica leaves, this heating plate beingcharacterized by the fact that the mica leaves forming the pad aremainl5 tained in a cambered position, tend to resume their level andaccordingly act as a spring maintaining the insulating unit in contactwith the plate. I

The drawing (Figs. 1 to 4) illustrates in crosssectional views fourways, as examples, in which the heating plate forming the object o! theinvention may be construed.

Fig. l is a cross-section of an embodiment construed the first way. Itshows a heating coil contained in'the closed insulator 2. Cap I isattached to plate 4 and maintains insulator 2 in contactwith thesaidplatebymeansolpadl 0! narrow mica leaves, which is distorted fromits flat position by being placed between insulator go Iandthe curvedcapi. Theleavesiormlngthis pad, because they are not subject to permanentdeiormation, tend to reassume a flat position and to occupy the positionindicated in mixed dotting. The pad thus acts as a spring and keeps 5insulator 2 in perfect contact with plate I.

Fig. 2 is a cross-section of the second way in which the convolutions oithe heating member arearrangedinsr uploltwo. InFlg.2,we see a group oftwo convolutions I and I arranged 40 in two insulating units. A concavecap 0 covers both convolutions of this group and cambers the leaves oipad Ill which is also applied to both convolutions.

Fig.3showsathlrdway,similartothatol 5 Fig. l, but with an open insulatorfrom which the heating coll ll protrudes, so that the said coiltransmltaflrst-tcinsulator l2,tbentoplate it. the pressure resultingiron: the camber oi pad I composed ct mica leaves.

Finally, Fig. 4 shows a way similar to. that of Fig. 3, in which theconvolutions oi the heating element are, however, arranged in groups oftwo, as indicated in the manner shown in Fig. 2.

It is possible to realize the invention with any number of convolutionsas regards the heating unit. These convolutions are providedeach with apad oi mica leaves, or are arranged in groups of two, with a pad foreach group. Other modiilcations will readily occur to those skilled inthe art. The scope of this invention, therefore, is to be limited by theclaims only.

I claim:

1. An electric heating plate comprising a supporting plate, aninsulating unit applied to said supporting plate, a heating elementhoused in the insulating unit, 'a pressing pad of a plurality of narrowmica leaves applied against the insulating unit, said mica leaves beingin cambered position and thus tending to reassume a fiat position and toact as a spring so as to hold the insulating unit against the supportingplate, and a concave cap covering said insulating unit and pressing pad.

2. An electric heating plate comprising a supporting plate, a pluralityof insulating units applied to said supporting plate and arranged ingroups oi parallel rows, heating elements housed in said insulatingunits respectively, pressing pads of a plurality of narrow mica leaves,each oi said pressingpads being applied against one group of insulatingunits, said mica leaves being in cambered position and thus tending toreassume a flat position and to act as a spring so as to hold saidinsulating units against the plate and concave caps, each of said capscovering one group of insulating units and one pressing pad.

3. An electric heating plate according to claim 2, wherein the heatingelement is housed in an open insulating unit, and wherein the micaleaves press directly against said heating element.

4. An electric heating plate according to claim 2, wherein the heatingelements are housed in open insulating units, and wherein the micaleaves press directly against said heating elements.

ETIENNE CHALLEI.

